The overall objective of the proposed research is to study the enzymes catalyzing the early steps of prostaglandin metabolism in the human placenta. The concentrations of these enzymes will be examined in placental tissue to determine whether they correlate with the onset of labor or the development of pathologic processes. These enzymes will be isolated and purified. Their characteristics will be establised, and the mechanisms controlling their activity will be sought. Using highly purified enzymes, the effectiveness of various synthetic prostaglandins and prostaglandin inhibitors will be examined.